They said the agency might also question his cousin and independent MLA Raghuraj Pratap Singh alias Raja Bhaiya in connection with these murders as some suspects are known to be cronies of the influential leader.
The CBI has registered four cases pertaining to three murders in Balipur village on March 2 and booked Raja Bhaiya in one of them on the complaint of Haq's wife. Raja Bhaiya had to resign from the Akhilesh Yadav government after his name cropped up in the case.
Recently, the agency has recovered a blood-stained wooden rod and ammunition belt with six live cartridges from various places here during its ongoing probe into the murder of Deputy Superintendent of Police Zia-ul-Haq and the two others.
The blood-stained ammunition belt was recovered from a box concealed in a house of Suresh Yadav, who was gunned down along with his brother and village pradhan Nanhe, official sources said.
The wooden rod, which too was blood stained, was recovered from another area in the village at the instance of local police officials who were being questioned by the CBI in the case, the sources said.